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><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="VIEW-PG-SETTINGS"
>45.62. <TT
CLASS="STRUCTNAME"
>pg_settings</TT
></A
></H1
><P
>   The view <TT
CLASS="STRUCTNAME"
>pg_settings</TT
> provides access to
   run-time parameters of the server.  It is essentially an alternative
   interface to the <A
HREF="sql-show.html"
>SHOW</A
>
   and <A
HREF="sql-set.html"
>SET</A
> commands.
   It also provides access to some facts about each parameter that are
   not directly available from <TT
CLASS="COMMAND"
>SHOW</TT
>, such as minimum and
   maximum values.
  </P
><DIV
CLASS="TABLE"
><A
NAME="AEN90543"
></A
><P
><B
>Table 45-63. <TT
CLASS="STRUCTNAME"
>pg_settings</TT
> Columns</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><COL><COL><COL><THEAD
><TR
><TH
>Name</TH
><TH
>Type</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>name</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Run-time configuration parameter name</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>setting</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Current value of the parameter</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>unit</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Implicit unit of the parameter</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>category</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Logical group of the parameter</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>short_desc</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>A brief description of the parameter</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>extra_desc</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Additional, more detailed, description of the parameter</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>context</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Context required to set the parameter's value (see below)</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>vartype</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Parameter type (<TT
CLASS="LITERAL"
>bool</TT
>, <TT
CLASS="LITERAL"
>enum</TT
>,
       <TT
CLASS="LITERAL"
>integer</TT
>, <TT
CLASS="LITERAL"
>real</TT
>, or <TT
CLASS="LITERAL"
>string</TT
>)
      </TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>source</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Source of the current parameter value</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>min_val</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Minimum allowed value of the parameter (null for non-numeric
      values)</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>max_val</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Maximum allowed value of the parameter (null for non-numeric
      values)</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>enumvals</TT
></TD
><TD
><TT
CLASS="TYPE"
>text[]</TT
></TD
><TD
>Allowed values of an enum parameter (null for non-enum
      values)</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>boot_val</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Parameter value assumed at server startup if the parameter is
      not otherwise set</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>reset_val</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Value that <TT
CLASS="COMMAND"
>RESET</TT
> would reset the parameter to
      in the current session</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>sourcefile</TT
></TD
><TD
><TT
CLASS="TYPE"
>text</TT
></TD
><TD
>Configuration file the current value was set in (null for
      values set from sources other than configuration files, or when
      examined by a non-superuser);
      helpful when using <TT
CLASS="LITERAL"
>include</TT
> directives in configuration files</TD
></TR
><TR
><TD
><TT
CLASS="STRUCTFIELD"
>sourceline</TT
></TD
><TD
><TT
CLASS="TYPE"
>integer</TT
></TD
><TD
>Line number within the configuration file the current value was
      set at (null for values set from sources other than configuration files,
      or when examined by a non-superuser)
      </TD
></TR
></TBODY
></TABLE
></DIV
><P
>   There are several possible values of <TT
CLASS="STRUCTFIELD"
>context</TT
>.
   In order of decreasing difficulty of changing the setting, they are:
  </P
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>internal</TT
></DT
><DD
><P
>      These settings cannot be changed directly; they reflect internally
      determined values.  Some of them may be adjustable by rebuilding the
      server with different configuration options, or by changing options
      supplied to <TT
CLASS="COMMAND"
>initdb</TT
>.
     </P
></DD
><DT
><TT
CLASS="LITERAL"
>postmaster</TT
></DT
><DD
><P
>      These settings can only be applied when the server starts, so any change
      requires restarting the server.  Values for these settings are typically
      stored in the <TT
CLASS="FILENAME"
>postgresql.conf</TT
> file, or passed on
      the command line when starting the server.  Of course, settings with any
      of the lower <TT
CLASS="STRUCTFIELD"
>context</TT
> types can also be
      set at server start time.
     </P
></DD
><DT
><TT
CLASS="LITERAL"
>sighup</TT
></DT
><DD
><P
>      Changes to these settings can be made in
      <TT
CLASS="FILENAME"
>postgresql.conf</TT
> without restarting the server.
      Send a <SPAN
CLASS="SYSTEMITEM"
>SIGHUP</SPAN
> signal to the postmaster to
      cause it to re-read <TT
CLASS="FILENAME"
>postgresql.conf</TT
> and apply
      the changes.  The postmaster will also forward the
      <SPAN
CLASS="SYSTEMITEM"
>SIGHUP</SPAN
> signal to its child processes so that
      they all pick up the new value.
     </P
></DD
><DT
><TT
CLASS="LITERAL"
>backend</TT
></DT
><DD
><P
>      Changes to these settings can be made in
      <TT
CLASS="FILENAME"
>postgresql.conf</TT
> without restarting the server;
      they can also be set for a particular session in the connection request
      packet (for example, via <SPAN
CLASS="APPLICATION"
>libpq</SPAN
>'s <TT
CLASS="LITERAL"
>PGOPTIONS</TT
>
      environment variable).  However, these settings never change in a
      session after it is started.  If you change them in
      <TT
CLASS="FILENAME"
>postgresql.conf</TT
>, send a
      <SPAN
CLASS="SYSTEMITEM"
>SIGHUP</SPAN
> signal to the postmaster to cause it to
      re-read <TT
CLASS="FILENAME"
>postgresql.conf</TT
>.  The new values will only
      affect subsequently-launched sessions.
     </P
></DD
><DT
><TT
CLASS="LITERAL"
>superuser</TT
></DT
><DD
><P
>      These settings can be set from <TT
CLASS="FILENAME"
>postgresql.conf</TT
>,
      or within a session via the <TT
CLASS="COMMAND"
>SET</TT
> command; but only superusers
      can change them via <TT
CLASS="COMMAND"
>SET</TT
>.  Changes in
      <TT
CLASS="FILENAME"
>postgresql.conf</TT
> will affect existing sessions
      only if no session-local value has been established with <TT
CLASS="COMMAND"
>SET</TT
>.
     </P
></DD
><DT
><TT
CLASS="LITERAL"
>user</TT
></DT
><DD
><P
>      These settings can be set from <TT
CLASS="FILENAME"
>postgresql.conf</TT
>,
      or within a session via the <TT
CLASS="COMMAND"
>SET</TT
> command.  Any user is
      allowed to change his session-local value.  Changes in
      <TT
CLASS="FILENAME"
>postgresql.conf</TT
> will affect existing sessions
      only if no session-local value has been established with <TT
CLASS="COMMAND"
>SET</TT
>.
     </P
></DD
></DL
></DIV
><P
>   See <A
HREF="config-setting.html"
>Section 18.1</A
> for more information about the various
   ways to change these parameters.
  </P
><P
>   The <TT
CLASS="STRUCTNAME"
>pg_settings</TT
> view cannot be inserted into or
   deleted from, but it can be updated.  An <TT
CLASS="COMMAND"
>UPDATE</TT
> applied
   to a row of <TT
CLASS="STRUCTNAME"
>pg_settings</TT
> is equivalent to executing
   the <A
HREF="sql-set.html"
>SET</A
> command on that named
   parameter. The change only affects the value used by the current
   session. If an <TT
CLASS="COMMAND"
>UPDATE</TT
> is issued within a transaction
   that is later aborted, the effects of the <TT
CLASS="COMMAND"
>UPDATE</TT
> command
   disappear when the transaction is rolled back. Once the surrounding
   transaction is committed, the effects will persist until the end of the
   session, unless overridden by another <TT
CLASS="COMMAND"
>UPDATE</TT
> or
   <TT
CLASS="COMMAND"
>SET</TT
>.
  </P
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